As a home burns in the background, a slurry bomber Monday drops fire retardant along one of the many ridges involved in the Fourmile Canyon fire west of Boulder. In addition to the three slurry planes that were in operation Monday, four more tankers will fly in today from other locations, officials said.

Tanker co-pilot Brock Hindman awaits the go-ahead to take off from Rocky Mountain Metropolitan Airport near Broomfield Monday. The fierce, dry gusts that aided the wildfire's spread also kept tanker planes grounded for hours while the blaze grew and spread.

Wildfire fanned by heavy wind charred more than 3,500 acres and an untold number of structures in the foothills west of Boulder on Monday, including the homes of four firefighters.

Laura McConnell, spokeswoman for the countywide coalition of fire departments tackling the blaze, said the four firefighters had been relieved of duty.

“We ask that you keep these people in your thoughts,” she said of all those who had lost property. No injuries to residents or fire crews had been reported.

More than 35 fire departments and agencies, including the U.S. Forest Service and the Colorado State Forest Service, responded to the blaze, which started about 10 a.m. Monday in the 7100 block of Fourmile Canyon Road, about 6 miles northwest of Boulder, Boulder County Sheriff’s Cmdr. Rick Brough said.

The cause of the fire, which may take several days to contain, has not yet been confirmed.

“The investigation will come after we get containment and control,” Brough said. For now, the goal “is just to get people out of the area and firemen into the area,” he said.

About 100 fire crews were on the line Monday, with about 70 on standby.

More local, state and federal aid is expected today, including four more air tankers to join the three that dropped fire retardant from about 5:15 to 8 p.m. Monday.

Planes will be back in the air this morning, McConnell said.

“At this point, we’re not even discussing containment and control,” she said Monday night.

Mandatory evacuations

Firefighters ordered mandatory evacuations of an area bounded on the west by the Peak to Peak Highway, on the east by U.S. 36, on the north by Lefthand Canyon Drive and on the south by Colorado 119.

Many structures were lost after winds gusting up to 45 mph buffeted flames in a pine forest, Brough said.

Brough said numerous roads in the region were closed, and some areas were too dangerous for fire crews to enter because of the steep, unstable terrain.

At 5 p.m. Monday, two jumbo-sized slurry planes carrying 3,000 gallons of retardant and a smaller plane carrying 700 gallons, which had been grounded because of high winds most of the day, were given the go-ahead to take off from Rocky Mountain Metropolitan Airport in Jefferson County near Broomfield.

U.S. Forest Service spokesman John Bustos said four more tankers will fly in from other locations.

“We’re ramping up,” he said. “We know that this fire is moving and we have to get out in its way. We need to sit on this as soon as possible.”

The fire filled the air with thick clouds of smoke.

“It’s jet black out here,” said David Jones, who lives in Gold Hill, about three-tenths of a mile from the fire. “There is ash falling from the sky.”

Massive smoke plume

The massive smoke plume was visible as far east as Denver International Airport.

Brough said wind spread the fire faster than firefighters could keep up, preventing them from being able to build a fire line.

“The winds will be a very large factor in how this plays out,” McConnell said.

Forecasters predicted the winds would reverse Monday and die down in the evening, forcing the flames back over the area already burned.

About 1,000 homes were evacuated. Shelters were set up at the North Boulder Recreation Center, New Vista High School and Nederland Community Center.

An animal shelter for larger animals was set up at the Boulder County Fairgrounds.

By Monday evening, about 100 people and 20 dogs were gathered at the North Boulder Recreation Center, including Charlene Austin, her husband and their two Labrador retrievers.

“We grabbed some pictures and things and got out,” Austin said. “It’s terrible not to know what’s going on out there, but it’s a blessing to know we’re OK and our dogs are OK.”

The American Red Cross opened an overnight shelter for fire evacuees at the Coors Events Center at the University of Colorado.

Monday night the Federal Emergency Management Agency authorized the use of federal funds to pay for up to 75 percent of the cost of fighting the Fourmile Canyon fire, including equipment use, repair and replacement, and mobilization of personnel.

Christopher N. Osher is a reporter on the investigation team at The Denver Post who has covered law enforcement, judicial and regulatory issues for the news organization. He also has reported from war zones in Africa.

Kirk Mitchell is a general assignment reporter at The Denver Post who focuses on criminal justice stories. He began working at the newspaper in 1998, after writing for newspapers in Mesa, Ariz., and Twin Falls, Idaho, and The Associated Press in Salt Lake City. Mitchell first started writing the Cold Case blog in Fall 2007, in part because Colorado has more than 1,400 unsolved homicides.

Joey Bunch was a reporter for 12 years at The Denver Post before leaving to join The Gazette in Colorado Springs. For various newspapers he has covered the environment, water issues, politics, civil rights, sports and the casino industry. He likes stories more than reports.